1. Field of the Invention
The present invention relates to fluid dispensers and in particular to a digital electronic data system for use in a fluid dispenser which includes means for setting unit price, computing the cost and quantity of fluid dispensed, and transmitting the data between dispenser, computing circuits, and display circuits with a minimum of interconnecting transmission means.
2. Description of the Prior Art
Presently, the computing of the delivery cost in a retail gasoline dispenser is almost exclusively accomplished by a mechanical variator. The computing function, whether accomplished mechanically or electronically by such a fluid dispenser, is nothing more than a multiplication of a presettable, variable quantity representing the cost per unit volume (usually cents/gallons) and a variable quantity representing cumulative volume of liquid actually dispensed (usually gallons); the product of these two quantities is the cost of liquid dispensed (usually dollars and cents).
The mechanical variator, driven by a flow meter through which all of the liquid being dispensed is passed, contains an elaborate gearing arrangement to accomplish this multiplication operation. By the use of gearing to drive a plurality of number wheels whose outside periphery is displayed through square openings in the dispenser face, the computer settings and outputs may be observed by the operator and customer. Usually, the display includes not only the cost of liquid dispensed, but the preset delivery cost of such liquid and the amount of liquid actually dispensed.
The mechanical system's computing function is entirely dependent upon the relative gear ratios within the computer between the preset unit volume price element and the amount of liquid dispensed element. The presettable unit volume price capability consists of nothing more than a means to physically shift the gearing within the computer, thereby varying the gear ratios to effect the desired result as exemplified in the computer output.
Because the computing function is performed by a mechanical apparatus, it is further common practice to provide a mechanical computing apparatus in each individual fluid dispenser in a particular installation. When it becomes necessary to alter the cost per unit volume, it is necessary for the station operator to alter the cost per unit volume settings in each individual dispenser. This operation requires the opening of a plurality of housings, and the maintenance of an inventory of change gears.
The mechanical systems and even more recent electronic fluid dispensers utilize an individual computing device in each fluid dispenser. Accumulation and transfer of data automatically from the dispensers to a remotely located receipt printing device, display console or the like have not been practical.
While such arrangements as the mechanical variator are satisfactory, it has been found that there are serious limitations which have, in the light of modern petroleum marketing technology, dictated the need for a device with flexibility both in the outward design appearance and in the inherent theory of operation. To this end, fluid dispensers with electronic computing elements and displays have recently become known in the art, such as exemplified by U.S. Pat. No. 3,813,527, issued May 28, 1974 to Earl M. Langston and assigned to the assignee of the present invention. While such arrangements have effected significant improvements these prior art systems still present problems.
For example, an all electronic fluid dispenser will more likely than not be installed in an already existing facility such as a gasoline service station or the like. Since most of these installations have been constructed to utilize mechanical fluid dispensers, the electrical wiring for the individual dispensers is typically routed through relatively small (3/4 inch diameter) electrical conduits or the like since the only electrical connections required have typically been those for conventional 110 volt alternating current. The conduits are typically encased in the pavement of the facility and removal or installation of additional conduits is costly. Correspondingly, electronic fluid dispenser systems as above-referenced have presented a significant difficulty in that they have required the installation of multiple conductor data lines or cables which frequently cannot be installed in existing conduits. Such systems have therefore been found to need improvements to provide simplicity in the theory of operation, the utilization of fewer parts in order for such a device to be price competitive with the mechanical value register and circuitry which will enable the transmission of data between fluid dispensers and a centrally located computing device and back to electronic displays with a minimum number of conductors.